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Key points
- The transition to daylight savings time leads to sleep disruptions every spring.
- A study found that people have serious decrements in attention when they’ve experienced seemingly small sleep disruptions.
- Daylight savings time may result in decreased cognitive performance, more traffic accidents, and an increase in heart attacks.
In stories, messing with time is always dangerous. Time travelers change the past and disrupt the present. You’d think we would have learned by now. But on Sunday, we’ll mess with time.
Daylight Savings Time and Sleep Disruption
Each year, we spring our clocks forward. We engage in universal time travel. This coming Monday, the alarm will call for you an hour earlier than last week. And less sleep is a brutal shock to the system.
We’ve all had nights when we just don’t sleep well. We wake up feeling exhausted. You’ve probably also experienced jet lag. You know the problems for the next few days until you adjust your internal clock. After a sleep disruption, you don’t think as well. You may be more irritable. You won’t be able to manage complex problems as well as after a good night of sleep.
But every year, we ask everyone in the country to have a week or two with disrupted sleep. When we spring forward during the transition to daylight savings time, we spend several days waking earlier. It can take a week or two to get things adjusted. Eventually, we’re able to go to sleep earlier and return to a normal cycle. We’ll return to a normal cycle, that is, if we survive the first week. But following the switch to daylight savings time, not all of us will make it.
Accidents and Daylight Savings Time
The change to daylight savings time is devastating. The sleep deprivation most likely contributes to an increase in car accidents (Fritz et al., 2020). Two aspects of the research demonstrate that sleep disruption is a potential cause of the increase in accidents.
First, the increase in accidents occurs in the week after the switch to daylight savings time during the spring and then returns to normal. When the timing of the switch changed a few years ago (moving earlier in the year), the accidents followed.
But the second aspect is even more important. During the fall switch, when we move our clocks backward, there is no increase in car accidents. The switch then gives people extra morning sleep.
All this shows that the change in lighting is unlikely to be critical. Instead having everyone in the country drive to work in the morning when they are all sleep deprived is a dangerous and deadly idea.
Cognitive Performance and Daylight Savings Time
Underlying some of these accidents is most likely a disruption in cognitive performance. In a compelling recent study, Nag, Yu, and Mitroff (2021) looked at online game performance before and after the transition to daylight savings time. The game is a visual search task; an online game in which people act like airport security screeners. They scan luggage and have to find dangerous items.
Nag and colleagues had access to seven years worth of data. People played the week before and the week after the transition to daylight savings time. In the week after, people were slower and more likely to make mistakes.
This massive experiment in time travel showed that people have serious decrements in attention when they’ve experienced seemingly small sleep disruptions.
Heart Attacks and Daylight Savings Time
But the transition to daylight savings time and the ensuing sleep deprivation doesn’t only kill you on the roads or through cognitive accidents. Suddenly being jarred awake an hour earlier than your system is used to is also risky for your heart. Heart attacks increase for the next few days after we spring forward (Sipila et al., 2016).
And just like the car accidents, the heart attack rate returns to normal after a few days. Critically, falling back in time in the fall doesn’t lead to the same increase in heart attacks. It is the loss of sleep, of having the alarm sound an hour earlier, that is related to the increase in heart attacks.
End Daylight Savings Time and Save Lives
When you look at news articles and websites about the transition to daylight savings time, there is plenty of reasonable advice. Most of the advice is focused on easing your sleep cycle around to the new normal. You could go to bed earlier each night and slowly set your alarm earlier. Make your transition gradual.
This advice is reasonable. If you can slowly adjust your cycle, do so. If you can avoid driving in the early morning next week, that might be wise as well. Usually, there are some drivers who are sleep-deprived and risky to be around. But next week, everyone will be sleep-deprived. Avoid that situation if you can.
But this is a big problem for everyone, so why are we expecting each of us to hopefully make small individual changes. The solution should match the size of the problem. End daylight savings time. I don’t care if we stick with the winter clock or the summer clock. That isn’t the issue. It is the change that is hard. Hard on our bodies and hard on our brains. End daylight savings time and possibly save lives.
References
Fritz, J., VoPham, T., Wright Jr, K. P., & Vetter, C. (2020). A chronobiological evaluation of the acute effects of daylight saving time on traffic accident risk. Current Biology, 30(4), 729-735.
Nag, S., Yu, A., & Mitroff, S. (2021). How is Daylight Saving Time still a thing?: Disruptions from Daylight Saving Time transitions lead to cognitive performance deficits. https://psyarxiv.com/37svc/.
Sipilä, J. O., Ruuskanen, J. O., Rautava, P., & Kytö, V. (2016). Changes in ischemic stroke occurrence following daylight saving time transitions. Sleep Medicine, 27, 20-24.
